Foldable semirigid airfoil for airborne vehicles

ABSTRACT

The present invention relates to a foldable, composite rigid and semirigid airfoil for use with airborne vehicles. The airfoil includes a rigid portion. A hinged rigid spar defines a leading edge of the airfoil. The trailing edge of the airfoil is defined by both a rigid aileron structure forming part of the rigid wing portion, and a cable which interconnects the rigid portion of the airfoil with a root point of attachment on the fuselage of the vehicle. Flexible material forms top and bottom airfoil surfaces of the collapsible wing portion when the airfoil is deployed, said airfoil surfaces being continuous with the aerodynamic form of the rigid wing portion.

United States Patent Sweeney [54] FOLDABLE SEMIRIGID AIRFOIL FORAIRBORNE VEHICLES [72] Inventor: Thomas E. Sweeney, 61 Overbrook Drive,

P9!9 1tN.- 49- [22] Filed: Nov. 19, 1969 [2]] Appl. No.: 877,945

[52] US. Cl. ..244/49 [51] Int. Cl ..B64c 3/56 [58] Field of Search..244/49, 46, 47, 43

[56] References Cited UNITED STATES PATENTS 1,928,336 9/1933Kindelberger .....244/49 3,330,50l 7/1967 Barber ..244/47 3,507,1504/1970 Stengel ..244/49 X Primary Examiner-Milton Buchler AssistantExaminer-Carl A. Rutledge Attorney-Darby & Darby [5 7] ABSTRACT Thepresent invention relates to a foldable, composite rigid and semirigidairfoil for use with airborne vehicles. The airfoil includes a rigidportion. A hinged rigid spar defines a leading edge of the airfoil. Thetrailing edge of the airfoil is defined by both a rigid aileronstructure fonning part of the rigid wing portion, and a cable whichinterconnects the rigid portion of the airfoil with a root point ofattachment on the fuselage of the vehicle. Flexible material forms topand bottom airfoil surfaces of the collapsible wing portion when theairfoil is deployed, said airfoil surfaces being continuous with theaerodynamic form of the rigid wing portion.

10 Claims, 4 Drawing Figures PATENTEUMAR I972 INVENTOR THOMAS E. SWEENEYATTORNEYS FOLDABLE SEMIRIGID AIRFOIL FOR AIRBORNE VEHICLES Thisinvention relates to semirigid airfoils, or sailwings, and moreparticularly to foldable, composite rigid and semirigid airfoilapparatus.

The use of airfoils of semirigid construction in which a rigid sparsupports a flexible wing form dates back to the earliest successesenjoyed by the pioneers of flight. Improved semirigid airfoil structuresof the sailwing type are disclosed in U.S. application, Ser. No.740,895, filed June 28, 1968.

Rigid wing structures presently known to the art are considerably moreexpensive to fabricate than semirigid or flexible winged aircraft.Efforts to fold rigid wings have resulted in complex and costlystructures. These costs are necessarily passed on to the purchaser ofsuch craft, which in many cases may be one of the growing numbers ofpersons who own a small plane for pleasure or business.

There is an increasing need for aircraft having folding wings for easein storage and transportation of the aircraft. While many folding wingdevices and methods have been developed for conventional hard wings,none is completely satisfactory from the consideration of weight, cost,complexity and maintenance requirements.

It is an object of the present invention to provide an aircraft having afoldable composite wing structure which is especially suited for low andmoderate speed aircraft.

Another object of this invention is to provide a composite wingstructure having both a rigid portion and a collapsible portion, thecollapsible portion comprising a semirigid airfoil or sailwing fillet.

A still further object is to provide an aircraft wing structure whichcombines the advantages of having both ailerons in a rigid portion forperforming functions such as roll control of the aircraft, as well as asailwing fillet portion which possesses favorable aerodynamiccharacteristics as well as an ability to collapse upon folding of thewing structure.

The present invention fulfills the aforementioned objects and overcomeslimitations and disadvantages of prior art solutions to existing problemby providing, in a preferred embodiment of the invention, a compositewing structure for use with airborne vehicles. The wing structure orassembly includes an outboard rigid wing portion and a collapsiblesemirigid airfoil or sailwing fillet portion. A hinged rigid spar memberdefines the leading edge of the wing assembly. The rigid airfoil portionincludes movable rigid ailerons which define the trailing edge of therigid wing portion, while a trailing edge cable extends in tensionbetween the rigid airfoil portion and a root point on the fuselage ofthe aircraft thereby defining the trailing edge of the collapsibleportion when the wing is deployed. Flexible materials which interconnectthe rigid wing portion and the fuselage and, defines upper and loweraerodynamic surfaces which are continuous with the aerodynamic wing formsurfaces of the rigid wing portion.

The invention will be more clearly understood from the followingdescription of specific embodiments of the invention together with theaccompanying drawing wherein similar reference characters denote similarelements throughout several views, and in which:

FIG. 1 is a fragmentary plan view of an aircraft having a compositefoldable wing structure according to the present invention;

FIG. 2 is a plan view of the aircraft of FIG. 1 illustrating the wingstructure in a folded position;

FIG. 3 isa fragmentary plan view of a composite, foldable wing assemblysecured to the top of the fuselage of an aircraft, and wherein the axesabout which the wings of the aircraft pivot when being folded arecoincidental;

FIG. 4 is a fragmentary plan view of a composite foldable wing assemblyillustrating both deployed and folded wing positions.

Referring now in more detail to the drawing, an aircraft includes aconventional fuselage portion 11, a tail portion 12 and two wingassemblies 23 and 14. Wing assemblies 13 and 14 are composite in thatthey each include a rigid wing portion 15 having an aileron 16 and wingtip fairing 17, as well as a collapsible wing portion 18.

Wing assemblies 13 and 14 possess similar elements and behave in thesame manner. Looking at wing assembly 13, a rigid hinged spar member 19defines the leading edge 20 of the wing form. Spar member 19 includes animmovable portion 21 which is secured, such as by welding, to fuselage11, and a movable portion 22 which is integral with and located withinrigid wing portion 15. Spar portions 21 and 22 pivot with respect to oneanother about a hinged axis designated reference character 23.

Collapsible wing portion 18 constitutes a wing assembly fillet whichinterconnects rigid wing portion 15 with the fuselage. Wing portion 18includes a trailing edge cable 24 which extends between a point ofattachment 25 on rigid wing portion 15 and a root point 26 on fuselagell. Trailing edge cable 24, together with the trailing edge of rigidwing portion 15 and aileron l6, define the overall trailing edge of wingassembly 13. In the deployed position shown in FIG. 1, wing assembly 13exhibits aerodynamic characteristics comparable to a conventional rigidor hard wing. In-flight roll is controlled by aileron 16 in aconventional manner.

Collapsible wing portion 18 further includes flexible wing material 27extends over and between spar member 19 and trailing edge cable 24 in amanner described in US. Pat. application, Ser. No. 740,895, filed June28, 1968. A seam of this flexible material is secured to cable 24, suchas by providing eyelets or lacing secured to the seam through whichcable 24 is passed. Material 27 is preferably made of dacron sailclothimpregnated with silicon, but may also be canvas, plastic or othersuitable flexible material. Material 27 is secured at its perimeter tofuselage l1, spar portion and wing portion 15. It is material 27 whichdefines the shape or form of collapsible wing portion 18 and thisaerodynamic wing form is continuous with the aerodynamic wing form ofrigid wing portion 15.

FIG. 2 illustrates wing assemblies 13 and 14 in their folded position,as would be the case when aircraft 10 is stored in a hangar or beingtransported, for example. The amount of room taken up by aircraft 10with wing assemblies 13 and 14 in their folded position is relativelysmall compared to the room taken up by the aircraft with its wingassemblies deployed. The folding of wing assemblies 13 and 14 isaccomplished either manually or by other suitable automatic meanscontrolled by the pilot of the craft. The distance between hinge axis 23and point of attachment 25 is slightly smaller than the length of theimmovable portion 21 of the spar member 19. Thus, when folded, theoutward extension of wing assemblies 13 and 14 is less than the outwardprojections of tail 12 of aircraft 10, as shown in FIG. 2.

Referring now to FIGS. 3 and 4, wing assemblies are shown which aresecured to the fuselage of the aircraft at its uppermost portion. FIG. 3shows composite wing assemblies 28 and 29 secured to the top of fuselage30 of aircraft 31, the aircraft being shown in phantom outline. Wingassemblies 28 and 29 are similar in structure and behavior. Wingassembly 29 includes a rigid wing portion 32 having an aerodynamic wingform which is continuous with the aerodynamic wing form of collapsiblewing portion 33. Rigid wing portion 32 includes an aileron 34 and aconventional wing tip fairing 35. Collapsible wing portion 33 includes atrailing edge cable 36 much like cable 24 which extends between a pointof attachment 37 on rigid wing portion 32 and a root point 38 on the topof fuselage 30.

Flexible material 39 of the type described as material 27 interconnectsrigid wing portion 32 with fuselage 30. A feature of aircraft 31 whichdistinguishes it from aircraft 10 is the provision of a common hingeaxis 40 about which wing assemblies 28 and 29 are both pivoted duringtheir folding between their deployed positions shown in full line inFIG. 3 and their folded position shown in phantom outline. As in thecase of aircraft 10 described for FIG. 2, wing assemblies 28 and 29 whenfolded do not project transversely from fuselage 30 a distance equal toor greater than the projection of tail 41 of the aircraft.

FIG. 4 illustrates yet another embodiment of the invention whereinfoldable composite wing assemblies 43 and 44 are secured together at thetop of fuselage 45 of an aircraft 42. In this embodiment a wingstructure similar to that described for FIGS. 1 and 2 is shown. A rigidwing portion 46 together with a collapsible wing portion 47 make up wingassembly 44. Rigid wing portion 46 includes ailerons 48 and 49 and wingtip fairing 50.

Collapsible wing portion 47 includes a trailing edge cable 51 whichextends between a point of attachment 52 on rigid wing portion 46 and acommon root point 53 for wing assemblies 28 and 29 on the top offuselage 45. Rigid wing portion 46 is pivotable about hinge axis 56. Asingle fixed spar member 54 is used for both wing assemblies 43 and 44.

The distance between hinge axis 56 and point of attachment 52 isslightly less than one-half the length of fixed spar member 54 suchthat, when folded, wing assembly 44 will project outwardly from fuselage45 a distance substantially equal to or less than one-half the span oftail 55 of aircraft 42, as shown in FIG. 4.

While the foldable wing assemblies 13, 29 and 44 have been described asbeing pivotable about axes 23, 40 and 53, respectively, it is of courseobvious that locking means (not shown) are provided within the scope ofthis invention to maintain the wing structures in the deployed positionduring flight without the possibility of their pivoting.

The embodiments of the invention particularly disclosed are presentedmerely as examples of the invention. Other embodiments, forms andmodifications of the invention coming within the proper scope of theappended claims will of course readily suggest themselves to thoseskilled in the art.

What is claimed is:

1. Aircraft apparatus comprising in combination, a body, a foldablecomposite airfoil assembly supported by said body comprising a rigidspar member at the leading edge of the airfoil assembly and extendingsubstantially the entire length thereof, said spar member beingconnected to said body, said airfoil assembly having a first rigidportion extending for and including at least a portion of the length ofsaid spar member, hinge means connected to said rigid airfoil portionfor pivoting said rigid airfoil portion with respect to said bodybetween a folded position and a deployed position, said airfoil assemblyalso having a second portion located between the body and said rigidportion of said airfoil assembly, said second portion including cablemeans secured between said body and said rigid portion of said airfoilassembly and flexible material attached to said body, said first portionof said airfoil assembly and to said cable means to complete the airfoilassembly, said cable means forming the trailing edge of said secondairfoil assembly portion, said flexible material being unrestrained inthe area between its connecting points to said body, said first airfoilportion and said cable means, and said cable also being unrestrainedexcept at its two ends where attached to said body and said rigidportion respectively.

2. Aircraft apparatus as in claim 1, wherein said hinge means connectssaid first and second portions of said airfoil assembly, said flexiblematerial being folded between the rigid portion of said airfoil assemblyand the body as said airfoil assembly is folded.

3. Aircraft apparatus as in claim 2, wherein said flexible material isconnected to a portion of said spar member which forms the leading edgeof said second portion of said airfoil assembly.

4. Aircraft apparatus as in claim 2, wherein said hinge means is locatedat said spar member.

5. Aircraft apparatus as in claim 4, wherein said spar member is formedin two sections both of which have portions which are outboard of saidbody, one of said spar member sections defining the leading edge of saidfirst rigid airfoil assembly portion and the other of said spar sectionshaving the flexible material connected thereto and defining the leadingedge of said second airfoil assembly portion.

6. Aircraft apparatus as in claim 5, wherein there are a pair of saidairfoil assemblies, each assembl bein located on a respective side ofthe body, the respective en 5 of each said cable of an airfoil assemblybeing connected at a common point on said body.

7. Aircraft apparatus as in claim 2, wherein there are a pair of saidairfoil assemblies, each assembly being located on a respective side ofthe body, the respective ends of each said cable of an airfoil assemblybeing connected at a common point on said body.

8. Aircraft apparatus as in claim 2, wherein there are a pair of saidairfoil assemblies, each assembly being located on a respective side ofthe body, the respective ends of each said cable of an airfoil assemblybeing connected to respectively different points on said body.

9. Aircraft apparatus as in claim 2, wherein there are a pair of saidairfoil assemblies, each assembly being located on a respective side ofthe body, said hinge means for each said airfoil assembly being locatedat a common point on said body.

10. Aircraft apparatus according to claim 9, wherein said hinge meanslies substantially in a longitudinal normally vertically extending planeof symmetry of said body.

1. Aircraft apparatus comprising in combination, a body, a foldablecomposite airfoil assembly supported by said body comprising a rigidspar member at the leading edge of the airfoil assembly and extendingsubstantially the entire length thereof, said spar member beingconnected to said body, said airfoil assembly having a first rigidportion extending for and including at least a portion of the length ofsaid spar member, hinge means connected to said rigid airfoil portionfor pivoting said rigid airfoil portion with respect to said bodybetween a folded position and a deployed position, said airfoil assemblyalso having a second portion located between the body and said rigidportion of said Airfoil assembly, said second portion including cablemeans secured between said body and said rigid portion of said airfoilassembly and flexible material attached to said body, said first portionof said airfoil assembly and to said cable means to complete the airfoilassembly, said cable means forming the trailing edge of said secondairfoil assembly portion, said flexible material being unrestrained inthe area between its connecting points to said body, said first airfoilportion and said cable means, and said cable also being unrestrainedexcept at its two ends where attached to said body and said rigidportion respectively.
 2. Aircraft apparatus as in claim 1, wherein saidhinge means connects said first and second portions of said airfoilassembly, said flexible material being folded between the rigid portionof said airfoil assembly and the body as said airfoil assembly isfolded.
 3. Aircraft apparatus as in claim 2, wherein said flexiblematerial is connected to a portion of said spar member which forms theleading edge of said second portion of said airfoil assembly. 4.Aircraft apparatus as in claim 2, wherein said hinge means is located atsaid spar member.
 5. Aircraft apparatus as in claim 4, wherein said sparmember is formed in two sections both of which have portions which areoutboard of said body, one of said spar member sections defining theleading edge of said first rigid airfoil assembly portion and the otherof said spar sections having the flexible material connected thereto anddefining the leading edge of said second airfoil assembly portion. 6.Aircraft apparatus as in claim 5, wherein there are a pair of saidairfoil assemblies, each assembly being located on a respective side ofthe body, the respective ends of each said cable of an airfoil assemblybeing connected at a common point on said body.
 7. Aircraft apparatus asin claim 2, wherein there are a pair of said airfoil assemblies, eachassembly being located on a respective side of the body, the respectiveends of each said cable of an airfoil assembly being connected at acommon point on said body.
 8. Aircraft apparatus as in claim 2, whereinthere are a pair of said airfoil assemblies, each assembly being locatedon a respective side of the body, the respective ends of each said cableof an airfoil assembly being connected to respectively different pointson said body.
 9. Aircraft apparatus as in claim 2, wherein there are apair of said airfoil assemblies, each assembly being located on arespective side of the body, said hinge means for each said airfoilassembly being located at a common point on said body.
 10. Aircraftapparatus according to claim 9, wherein said hinge means liessubstantially in a longitudinal normally vertically extending plane ofsymmetry of said body.